javascript函数返回对象的问题？

Question

var processMessageData = function(b) {

    if (!b) {

        return null 

    }

    if (typeof (b) == "string") {

        b = (new Function("return " + b))()

    }

    if (!b.id) {

        return null 

    }

    var a = (new Function("return " + $("#" + b.id).val()))();

    a.requestFields = b.requestFields || {};

    a.responseFields = b.responseFields || {};

    return a

}

Answer 1

假设$("#" + b.id).val()取到的是{requestFields:123}，那替换一下就成为了function f() {  return {requestFields:123} }了，相应的a就是返回的对象{requestFields:123}